1. Field of the Invention
This invention relates generally to flashing used in buildings to provide a seal between a surface and a member projecting therefrom; and more specifically, this invention relates to flashing applied to seal an opening in a roof surface and to a vent that projects through an opening in said surface. Still more specifically, this invention relates to apparatus that combines a vent hood for covering a vent pipe that projects through an opening in a metal roof surface with flashing that seals said metal roof surface opening.
2. General Background
Various kinds of vents commonly project up through openings in the roof of a building to release indoor steam and/or other gases to the atmosphere; these include plumbing vents such as bathroom and laundry room exhaust vents, and kitchen range vents. Such vents may include a cover or hood and a screen to prevent rain, insects and other pests from entering into the vent; see, for instance, the vent hood depicted in FIGS. 1, 2, the use of which is limited, however, to composition roofs. To install such a vent hood, lead and soft malleable metals in sheet form have been used as a flashing material because of the ease of deforming the material to follow the irregular contours usually presented by the surface of the roofing material. If, however, one attempts to use a vent hood of the kind depicted in FIGS. 1, 2, on a metal roof, it will tend to leak because it does not conform to the irregular surface of a metal roof. Nevertheless, prior to my invention, such a vent hood has been used even on metal roofs for lack of a better alternative, but doing so has required extensive, labor-intensive, cutting and fitting of flashing in order to create as adequate a seal as the circumstances would permit.